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Sleep Apnea Newsletter: Portable & Reliable CPAP Power for Travel

If I use a CPAP treatment for sleep apnea every night at home, what can I do to continue treatment when the electricity fails, I have to travel, or when I want to get away from civilization for a vacation?

I have been following up these questions for several years, and every year there are more options and the solutions seem to become easier. The CPAP devices (and PAP devices--any device using Positive Airway Pressure) are lighter and smaller. Some have the ability to use almost any power source, even on an airplane; and now there are compact, lightweight batteries for camping, hunting, and sailing. With newly available equipment, you can get 1-2 night's sleep on a single charge with a battery+CPAP combination weighing under 10 pounds.

If you are concerned about being able to use your PAP during a power outage at home, you can save some money and use your regular CPAP and a deep-cycle battery. See: How to Sleep (Almost) Anywhere with CPAP: Back-up power and battery systems for travel.

Since we published that information, there are some recent technological developments that will make sleeping while camping, hunting, sailing, or traveling more of a pleasure, and less of a chore. With newly available equipment, you can get 1-2 night's sleep on a single charge with a battery and CPAP combination weighing under 10 pounds.

CPAP units are now very compact and light, and some have a universal power supply--able to use the two major world standards: 110V 60 Hz, or 220 V 50 Hz.--simplifying international travel. Also, some devices can accept direct battery connections, or can use a battery with a suitable inverter, which converts the electicity from the battery to a type that the PAP device can use. Bilevel and autopressure devices can also be run on battery power. Batteries are now available in very small, lightweight lithium-ion units, as well as in deep-cycle lead-acid units using Absorbed Glass Mat (AGM) technology. Deep-cycle batteries use robust construction and can be discharged to 80 percent of capacity; marine batteries can yield about 60 percent. The AGM technology is robust and the most suitable type of lead-acid battery for home use because these batteries are spillproof.

Criteria for Travel by Air, Plane and Camping

For travel that requires me to carry the gear, I want a small, lightweight device to minimize my total luggage and to make it easier to keep the CPAP in my carry-on bag. For this article, I have assumed that a CPAP unit of 3 pounds or less is suitable for camping and travel. For longer trips by air or train I want to be able to use the unit when I nap or sleep--I need either a very light, compact battery or to be able to use the outlet power on the train or plane. If you want to use your CPAP in flight, clear this with the medical unit of the airline well before you travel. Not all CPAP units are capable of using the special electrical frequency on aircraft--check with your CPAP manufacturer and the airline. The battery unit should be tested safe for air travel by a government agency--see below regarding screening by the Transportation Security Agency (TSA). Also, effective 1 Jan 2008 the TSA has new restrictions on lithium batteries.

For camping, I would look for the smallest, lightest CPAP device that supports direct battery input (12V) without use of an inverter--an inverter changes direct current (DC) from a battery to alternating current (AC) that is like household electricity). Consider also the weight of charger, and your access to mains/household electricity to recharge the battery.

For travel in a vehicle (RV, car, boat) or for home use with battery backup, heavier units may be perfectly suitable. You can use your regular CPAP if you add a battery backup capability. If you are buying a new PAP unit, or can afford a second unit for travel or backup, then you would look for a CPAP unit that supports direct battery input (12V without use of an inverter); or a CPAP unit with a complete battery backup setup; or you would fashion a suitable battery backup system. The AGM (glass mat) is a lead-acid battery technology that is the most suitable and economical for home or for use in a vehicle (car, RV, boat). However, some of the new integrated CPAP+battery units might be a good option, and a preconfigured battery system would be a lot easier (but more costly) to set up than assembling a system from scratch.

For convenience, consider a complete battery pack including a charger, provision for charging from mains (mains=regular electricity service), an inverter if required, and a DC power cord that matches your chosen CPAP unit. You can find these based on lead-acid as well as lithium ion. Weight and price are the big differences: lead acid weighs more, lithium-ion costs more. If you decide to use lead acid, consider getting two smaller batteries rather than a single one to meet your needs: I found a large battery very difficult to move around the house.

Other Factors to Consider in Your Plan

Consider the cost of a travel-only or backup-only CPAP, the cost of the battery, capacity of the battery, and how long it takes to charge.

It is a good idea to review your plan with your primary care doctor or the sleep specialist who oversees your apnea diagnosis and treatment. If you usually use a humidifier, should you continue to do so while traveling? Is the CPAP unit you are considering comparable in treatment effect to the one you normally use?

Be sure to have a strategy for recharging. If you have a vehicle, can you use it to recharge without risk of ruining your vehicle's electrical system? Can you take the battery to a source of mains current or a service station? Can you take the time for a slow, trickle charge, which will give you more power than a fast recharge?

At home, before leaving on a trip, connect your travel system and use it until it stops. Clock the use time so you will have an estimate of how long a fully charged system will operate at that ambient temperature. A battery wlll provide less power when cold. Why not just rely on spec sheets from the manufacturer? Well, there are several variables that go into computing available usage time; even if you can figure out how to compute usage for your setup, you might not have an accurate answer. For example, there are no industry standards for battery capacity; your usage patterns on CPAP may create a different current usage than the CPAP manufacturer has published; your battery may be old or cold; you may have the wrong size of fuse; and so on. Also, since the CPAP you have chosen for travel may differ in its treatment efficacy, it's best to see if you sleep well using it. If there is a problem, better to find out at home!

Most CPAP devices will need an inverter to change the battery direct current (DC) voltage to alternating current (AC). Some CPAP devices accept a direct-to-battery connection through a device-specific cable, although they may have an internal inverter circuit. Because inverters waste some energy as heat, a CPAP unit that actually ran on DC would be more efficient.

Check with the manufacturer about using a humidifier when running on battery power. Most inverters produce an imperfect simulation of alternating current and can burn out the humidifier. Do NOT attempt to run a heated humidifier from an inverter or battery backup system unless the manufacturer of your unit specifically permits this. Also check with the manufacturer about suitable inverter options, proper cables, and other issues for that brand of CPAP.

Lithium Ion is a very dense form of storage; it is small and lightweight for the power it delivers. Although it is also expensive and slow to recharge, it seems like the best choice where weight is a premium: travel and camping.

W A R N I N G: A shorted battery will generate intense heat and may cause fire. Some lithium batteries have caught fire. Such an event, although rare, can pose a serious hazard especially on board an aircraft.

Effective 1 Jan 2008, the Transportation Security Agency (TSA) has placed restrictions on the total amount of lithium batteries that can be taken on an aircraft and/or in checked baggage. Unless there is a waiver for medical uses, batteries such as those listed here as adequate for a CPAP unit would seem to fall under this ban. See new regulations under TSA below.

Where weight and bulk are not the primary consideration, any CPAP unit for home use can be hooked up to a battery. Also, the most electricity for the money will be from the heavy, bulky deep cycle lead-acid batteries. The best technology is the deep-cycle absorbed glass mat (AGM) type: spill-proof, sturdy, economical.

The PAP devices listed here are examples of currently available models. There are several manufacturers, and any PAP device, new or old, can probably be fitted with a battery power supply. You can use your present device and simply add a battery system.

Terry Collins's Independant/Remote Power Information Page Terry reports in some detail on how he created his power sources for short and longer-term camping and for a reliable source in the event of a power outage. Helpful reading. Note the prices are probably in Australian dollars.

Where can you find help and support? The technical department of each CPAP manufacturer will be able to provide information about their own devices. Other people who have experience in running electrical devices in the absence of power from the electrical utility grid include people who travel in recreational vehicles (RV), sailors, and people who by ideology or necessity live "off the grid," with little or no electrical power from a utility,or where the power supply is not reliable.

Tech note: Powering ResMed products with batteries

Includes general information on types of lead-acid batteries as well as specific recommendations for ResMed products, including flow generators and humidifiers.

How to Live Without Electricity & Like It (Paperback) by Anita Evangelista

Dealers in RVs and people who provide services to RV owners. Good information in handbooks written for RV Owners, see the chapter on batteries.

Safety Warning

Making, installing, and using a battery backup system can damage CPAP equipment, or may cause personal injury, fire, or explosion. Therefore, consult with your physician, home care company, and/or the manufacturer of your CPAP before you start. The services of a qualified electrician should be used. The Safety Warnings are part of this document and should be read together with it. Safety Warnings for Battery Operation of CPAP Devices (lead-acid type)

There *must* be a fuse to protect the battery from a short circuit that could lead to a battery explosion or meltdown. The fuse should be in the (+) line as close to the battery terminal as possible.

Flying; Transportation Security Administration (TSA)

These are the people who screen passengers and their luggage before flight.

I have queried the TSA and gotten a boilerplate answer that doesn't tell me clearly if I would be able to carry a lithium ion battery aboard a plane or even send it as stowed luggage. I learned that CPAP devices are allowed, also:

Any other disability-related equipment and associated supplies... The limit of one carry-on and one personal item (purse, briefcase or computer case) does not apply to medical supplies, equipment, mobility aids or assistive devices carried or used by a person with a disability... If you have medical documentation about your medical condition or disability, you can present this information to the security officer to help inform him or her of your situation. We don't require this documentation and it will not exempt you from the security screening process. (TSA)

For more information from the TSA, call toll-free at 866-289-9673 Transportation Security Administration (TSA) or see the TSA website at www.tsa.gov

I suggest you research the TSA requirements for yourself before you travel. Personally, I would insist on keeping my CPAP unit with me, but would accept sending a battery in the luggage, assuming it is permitted on the flight. Also, I would not take a battery with me on a flight unless my destination involved camping out, and even then I would consider shipping the battery separately.

If you plan to use your CPAP during a flight, get advance permission from the airline, check the TAS rules, and make sure your device can run on the electricity on the plane--check with the CPAP manufacturer. To see if you will have access to an electrical outlet, use
SeatGuru which provides detailed information on airplane seating. You will need to find out what type of aircraft will be used on your flight(s). Many planes provide power suitable to a laptop which may not be adequate for your CPAP; some power is AC, some DC. You will need to research the details and get any necessary inverters, converters, or plug adapters. To repeat, some aircraft electrical sources are not 50 or 60 HZ and not all CPAP devices can handle that.

W A R N I N G: A shorted battery will generate intense heat and may cause fire. Some lithium batteries have caught fire. Such an event, although rare, can pose a serious hazard especially on board an aircraft. See new regulations below.

Effective 1 Jan 2008, the Transportation Security Agency (TSA) has placed restrictions on the total amount of lithium batteries that can be taken on an aircraft and/or in checked baggage. Unless there is a waiver for medical uses, batteries such as those listed here as adequate for a CPAP unit would seem to fall under this ban.

The TSA site is not easy to interpret, however they state: "Quantity limits apply to both your spare and installed batteries. The limits are expressed in grams of “equivalent lithium content.” 8 grams of equivalent lithium content is approximately 100 watt-hours. 25 grams is approximately 300 watt-hours." You will need an electrician to interpret this or get the specs from the battery manufacturer. Cell phones or laptop computers typically are less than the 8 grams of equivalent lithium content. The larger battery, up to 25 grams equivalent lithium content, must be installed in a device and the TSA recommends it be taken as carry-on luggage; the device should be protected against being turned on and against possible short circuits.

New regulations took effect on January 1, 2008, regarding airline passengers traveling with lithium batteries. This safety issue is regulated by the U.S. Department of Transportation's (DOT) Federal Aviation Administration. TSA has and will continue to work closely with the FAA on aviation safety and security issues.

The DOT regulation specifically prohibits carrying spare lithium batteries in checked baggage. However, passengers may still place a portable electronic device in checked baggage with the batteries installed. DOT also permits batteries installed in portable electronic devices in carry-on baggage.

Additionally, DOT permits passengers to take spares of most types of lithium batteries in their carry-on baggage provided they take measures to cover the battery terminals. A short circuit can occur if a battery's terminal touches metal. To prevent this, passengers must keep spare batteries in their original packaging, a battery case, or separate pouch or pocket. Passengers also have the option of placing tape over the battery terminal of unpackaged batteries to insulate the battery terminal.

Passengers are limited to taking two larger lithium batteries onboard, such as the extended-life laptop computer batteries. For more information regarding the specific types of batteries allowed in airline baggage, please visit the DOT Pipeline and Hazardous Materials Safety Administration website at http://safetravel.dot.gov. For additional questions or comments, call the DOT Hazardous Materials Information Center at (800) 467-4922. (emphasis added)

This is a preliminary survey, not a complete listing. I have not done any hands-on evaluation and rely on information provided by the manufacturer or Internet retailers. Values of measurements of the various items are rounded. Links provided are for the convenience of readers, and no compensation has been received for their listing. Consider the information here as a jumping-off point for your own research.

This document provides information only. The reader is solely responsible for any use made of this information.

Our publications (online, email, print, or any other communications or phone contacts) do not provide medical advice or a professional service. No one including the publisher, editors, editorial advisors, or the authors of any material in this site is engaged in providing any medical or professional advice or services through the publication, distribution or sale of articles, books, materials, tests or quizzes, on this site or in communications by phone, email, or any other means. Persons with suspected or diagnosed sleep apnea syndrome or any sleep disorder or other condition should consult with a physician and other qualified professionals for advice concerning their own treatment.